chore(publicip): internal/publicip/ipinfo package

internal/publicip/ipinfo/multi.go

@@ -0,0 +1,54 @@
+package ipinfo
+
+import (
+	"context"
+	"net"
+)
+
+// FetchMultiInfo obtains the public IP address information for every IP
+// addresses provided and returns a slice of results with the corresponding
+// order as to the IP addresses slice order.
+// If an error is encountered, all the operations are canceled and
+// an error is returned, so the results returned should be considered
+// incomplete in this case.
+func (f *Fetch) FetchMultiInfo(ctx context.Context, ips []net.IP) (
+	results []Response, err error) {
+	ctx, cancel := context.WithCancel(ctx)
+
+	type asyncResult struct {
+		index  int
+		result Response
+		err    error
+	}
+	resultsCh := make(chan asyncResult)
+
+	for i, ip := range ips {
+		go func(index int, ip net.IP) {
+			aResult := asyncResult{
+				index: index,
+			}
+			aResult.result, aResult.err = f.FetchInfo(ctx, ip)
+			resultsCh <- aResult
+		}(i, ip)
+	}
+
+	results = make([]Response, len(ips))
+	for i := 0; i < len(ips); i++ {
+		aResult := <-resultsCh
+		if aResult.err != nil {
+			if err == nil {
+				// Cancel on the first error encountered
+				err = aResult.err
+				cancel()
+			}
+			continue // ignore errors after the first one
+		}
+
+		results[aResult.index] = aResult.result
+	}
+
+	close(resultsCh)
+	cancel()
+
+	return results, err
+}